"It's such a subtle and delicate situation when they're that young," says Spears, who should know what it's like to be young and in entertainment, "so you just have to use constructive criticism and be there for them and just show them support."

As for what she looks for as a judge, she says, "I'm really just looking for (someone who) shows spark and spunk and someone that's meant to do what they're doing and it shows."

Jack Osbourne says vision problem led to M.S. diagnosis

Jack Osbourne's first clue that something was wrong came when he had trouble seeing.